The stomach is a stretchy, muscular bag, which stores food and helps to break it down (digestion). It is in the upper left-hand side of the tummy area (abdomen). An adult’s stomach is about 25cm long, but can expand to hold about 1 litre of food.
The upper part of the stomach joins to the oesophagus. The oesophagus is a muscular tube that connects the mouth to the stomach. The lower part of the stomach joins to the first part of the small bowel (the duodenum). The pancreas, gall bladder and liver are close to the stomach. They produce juices and enzymes (chemicals) that help digest food.
The wall of the stomach has four layers:
- The mucosa is the inner layer (stomach lining). It contains glands that produce enzymes and acid, which help digest food.
- The submucosa attaches the mucosa to the muscularis.
- The muscularis is a layer of muscle. It squeezes the stomach walls together to help move partly digested food into the small bowel.
- The serosa is a strong outer membrane which covers the stomach.
After you have chewed and swallowed your food, it passes down the oesophagus to the stomach. The stomach churns up food and mixes it with acid and enzymes. This breaks the food down into much smaller pieces. This is how our bodies get the nutrients needed to give us energy and keep us healthy.
The stomach muscles squeeze together (contract) so that semi-solid food passes from the stomach into the small bowel. Digestive juices from the stomach and pancreas help the small bowel take in important substances from food. These include vitamin B12, iron and calcium.